The art of flour mills manufactured on a small scale for home use is extremely old, but the demand for such mills has evidenced a revival in recent years. The modern demand stems from the desire of many consumers to produce fresh, whole-grain flour in a fresh state, without addition of preservatives or additives. While some equipment is available to meet this demand, most mills are difficult to maintain due to their high rotational speeds. They often have little or no adjustment capability, which is extremely important if one is attempting to produce fine cake flour. They also are typically subject to overheating, which can damage the flour.
The basic features of the flour mill were illustrated many years ago in the Patent to Arnold, U.S. Pat. No. 3,468, which was patented in 1844. This prior disclosure shows a grain mill having a stationary disc mounted to a framework and a powered disc rotatably journaled by the framework. No adjustment mechanism is visible in this disclosure, which is directed to the particular features of the metal cutters.
A similar structure was illustrated in a paint mill described in U.S. Pat. No. 7,630, which issued in 1850. Stationary and rotatable discs are mounted on opposed shafts. The non-rotatable disc is adjustable by means of a hand crank. Adjustment provided by this arrangement appears to have been rather coarse, however, it might have been acceptable at the speeds available for hand-operated grinding processes.
Later refinements in mills for various purposes are illustrated by the following prior patent disclosures: Baker U.S. Pat. No. 330,665, patented in 1885; Durham U.S. Pat. No. 891,050, patented in 1908; Richards U.S. Pat. No. 927,077, patented in 1909; Kihlgren U.S. Pat. No. 1,098,325, patented in 1914; Winegardner U.S. Pat. No. 1,286,865, patented in 1918; and Hogan U.S. Pat. No. 1,435,130, patented in 1922. These patents are primarily concerned with the configurations for moving material outward along the grinding surfaces of opposed discs in response to rotational and centrifugal forces.
The present disclosure arose from an effort to improve upon available commercial flour mills sold for consumer use to produce fresh kitchen flour. Experience with available mills encountered overheating of the flour, misalignment of the discs, and subsequent damage to the grinding surfaces. Many such mills have a very low flow rate through them and require considerable time to produce a usable amount of flour. Many of the available mills were also found to lack adjustment capabilities or the available adjustment features were too crude to permit milling of fine flour, such as is used for baking cakes. The mill described herein is capable of producing coarse or fine flour at a reasonable rotational speed and without dangerous overheating of the grain or flour during the milling process. The mill also makes use of a relatively economical material for the grinding discs, substantially reducing the production costs of the mill itself. Finally, the mill is capable of precision milling due to the coaxial support provided to both discs through the medium of the supporting housing structure. The mill design makes maximum use of gravitional flow to assure proper feeding and through-put between the grinding discs in conjunction with the available rotational and centrifugal forces.